The Baltic Yearbook of International Law is published under the auspices of the Baltic Editorial Board within the framework of cooperation between the Riga Graduate School of Law and Brill/Nijhoff Publishers. The Yearbook aims to bring to the international debate issues of importance in the Baltic States, providing a forum for views on topical international law themes from Baltic and international scholars. The first volume appeared in 2001 with a symposium on the question of the international legal status of the Baltic States. The Yearbook contains state practice reports from Estonia, Latvia and Lithuania, thus serving as an important source of international law unavailable elsewhere. From time to time the Yearbook offers articles discussing the history of international law and current issues in Eastern Europe and the Russian Federation, thus making regional discourse more accessible to a wider global audience. Volume 20 is devoted to the theme of Estonian Tradition in International Law and was put together mainly by international law scholars at the University of Tartu, the oldest Estonian university. It also includes papers from a symposium for non-Western States on international law and cyber operations, co-organized together with CCDCOE, the NATO Cooperative Cyber Defence Centre of Excellence, in Tallinn. The open access version of this volume of the Yearbook was funded by grant PRG969 of the Estonian Research Council and the contribution of the CCDCOE, the NATO Cooperative Cyber Defence Centre of Excellence.